The present invention relates to the field of flour separation. The invention discloses a method for the separation of flour, in particular wheat flour, compositions for the separation of flour and the use thereof. Further the invention relates to a fraction consisting essentially of gluten, and a product comprising said fraction.
The industrial implications of flour and the products obtained from its separation are receiving increasing attention. Flour may be separated into fractions of starch, gluten and fibres. In the separation of flour the very nature of the flour protein, i.e., gluten, as being water insoluble presents a challenge desirable to overcome.
Gluten consists primarily of the proteins, glutenin and gliadin. Upon hydration and during processing gliadin and glutenin interact to form a network. Proteins of wheat flour form a network with disulphide bridges (S-S-bridges). The network is stronger, the more sulphur bridges are present. The network entraps carbon dioxide formed during fermentation creating the characteristic elasticity of the wheat flour dough. The elastic properties of gluten are due to the glutenin fraction and the viscous properties come from the gliadin fraction. It is therefore a fact that the quality of the flour for the purpose of baking is highly dependent on the amount of gluten contained in the flour. Gluten may be added to flour of poor quality to improve the baking properties of the flour.
Prior art attempts to separate wheat flour have been made. U.S. Pat. Nos. 4,217,414, 3,951,938 and UK 2 032 245 all describe examples of methods for the separation of wheat flour and the recovery of wheat gluten. Here the separation of wheat flour into gluten and starch fractions are performed by the means of mechanical processing. The mechanical separation methods described in the references are centrifugation, screening, decanting or milling.
The application of mechanical techniques of separation provided for fractions of gluten and starch. However, to obtain less contaminated fractions effort was directed toward improving the purity of the fractions.
The addition of enzymes to the flour or dough proved to be a successful way of achieving an improved separation. The added enzymes are capable of reacting with the flour and thereby improve the separation quality of the gluten.
In the prior art numerous references disclose such use of gluten improving enzymes. Among those are Weegels et al. (Weegels, P. L., Marseille, J. P., and Hamer, R. J., 1992, Starch/stxc3xa4rke 44, 2, pp. 44-48) who describe the use of enzymes as a processing aid in the separation of wheat flour into starch and gluten. The enzymes mentioned are lipase, hemicellulase and cellulase.
Further, Christophersen et al. (Christophersen, C., Andersen, E., Jakobsen, T. S., and Wagner, P., Starch/Stxc3xa4rke, 1997, 49, pp. 5-12) describe the successful use of a xylanase to improve the yield of gluten and starch, without apparent negative effects on the gluten quality.
Formerly it has not been possible to obtain gluten fractions from prior art processes of flour separation having a high content of pure protein, such as gluten fractions consisting essentially of gluten, having a very low content of starch or fibres of the xylan or arabinoxylan type.
It is an object of the present invention to provide for a method for the separation of flour, in particular wheat flour, into one gluten fraction and at least one other fraction, comprising the steps of:
a) mixing the flour and a liquid to obtain a dough,
b) separating the dough into a fraction comprising gluten and at least one other fraction,
c) recovering at least the gluten fraction, characterized in that an oxidoreductase is added at any of steps a), b) or c).
In another aspect the invention relates to a method for the separation of flour into one gluten fraction and at least one other fraction, comprising the steps of:
a) mixing the flour and a liquid and at least one oxidoreductase enzyme obtaining a dough,
b) separating the dough into a fraction comprising gluten and at least one other fraction,
c) recovering at least the gluten fraction.
It should be mentioned that the method can also be carried out as described above where the oxidoreductase(s) in question is(are) added to the (dry) flour. If the oxidoreductase(s) in question has(have) been added to the flour the oxidoreductase(s) has(have) time to react with O2 (e.g., from the air or by addition of pure O2) to provide a flour composition with the desired gluten quality.
The present invention permits the separation of gluten from any quality of flour, in particular wheat flour, even from flour of poor quality, such as flour used for fodder.
Thus advantages of the invention may include improved yields, more pure gluten and/or higher quality of gluten.
By the present method an improved separation of flour, in particular wheat flour, is obtained. The improvement in the separation of the flour increases the yield of gluten and starch fractions by providing a more efficient method of separation. Further according to the invention the separated gluten is of a higher quality, (i.e. less contaminated with other flour components, such as starch or fibres) than gluten fractions obtained according to the prior art.
Further the invention relates to a composition for the separation of flour, in particular wheat flour, into one gluten fraction, and at least one other fraction, comprising at least one oxidoreductase enzyme.
The compositions of the invention may be used for the separation of flour, in particular wheat flour.
In a further aspect the invention relates to a flour composition comprising any of the oxidoreductases mentioned below.
The gluten fraction obtained may be added to flour to increase the gluten content, such as to enhance poor quality flour, and thereby improving the baking quality of the flour.